NEWCASTLE United boss Bobby Robson last night revealed that £20m-rated Kieron Dyer has been suffering a stress fracture for much of the season.

The England starlet, who was thought to have a shin-splint problem, undergoes a bone graft today in a bid to finally banish his injury nightmare.

It is Dyer's second operation in a fortnight, but Robson expects the 22-year-old midfielder to be fit for the start of next season.

He said: "He'll have bone grafted from his hip to his shin. It turned out to be a stress fracture, not shin splints. Sometimes these things don't show up on a scan.

"That's why the kid had so much pain. He must have done it in mid-season. That means all the time Alan Shearer was out injured, Kieron was playing up front for two months in pain.

"They will put a pin in his leg and the specialist thinks there's a good chance he'll start next pre-season, but he might miss the first week.''

Dyer acted as a makeshift striker while Shearer was out for nine weeks after surgery for tendinitis in his left knee.

The United skipper broke down in a practice match a week ago, only a fortnight after making his comeback, and has since been under specialist supervision.

But Robson has refused to rule him out of today's Tyne-Tees derby clash with Middlesbrough, in which £7m Carl Cort returns to first-team action after almost six months on the sidelines with hamstring trouble.

The former Wimbledon striker scored twice in five appearances before succumbing to an injury which required surgery.

Robson said: "Our only slight doubt is Alan. He jarred his knee but it's settling down - it's a lot better than last week.

"The specialist doesn't think there's a lasting problem. If he's fit, he'll start. If he's not, he won't be involved at all because we won't take any risks with him.

"But Carl will start and I think he's excited. He played in the reserves this week and looked good. I brought him off late on as a precaution, but he's trained every day this week.

"I have no doubt he will last the distance tomorrow. If he doesn't, I'm getting in a taxi and going home!

"Carl has been a terrific pro and not many would have had a better mentality in his situation. It was a two-month injury - and it has lasted seven in all.''

Scottish Under-21 international Steve Caldwell will continue at the heart of the United defence following Alain Goma's £4m move to First Division leaders Fulham.

The Frenchman fired a parting shot at the Magpies, accusing them of lacking ambition.

Chairman Freddy Shepherd responded by saying: "That's rich coming from someone who played less than 50 per cent of our games through injuries.''

And Robson was yesterday also quick to hit back. "I think what Alain Goma has said is very unprofessional,'' said the United manager.

"I hate it when players leave a club and then embark on that course. I wouldn't have thought his new club would be happy about it either.

"I find it distressingly sad. We paid a lot of money for him and he was paid a lot of money while he was here, but he was unhappy and wanted to go.

"We've got money to spend now, but there's no panic. We just need to sit down and look at the whole situation.

"My young back-four did very well at Everton a fortnight ago when Goma surprisingly pulled out with an injury.''

Robson, meanwhile, was yesterday trying to persuade Chilean midfielder Clarence Acuna not to follow Nolberto Solano back into international football.

The United duo could be in opposition a week on Tuesday in a World Cup qualifier when Peru host Chile.

"I can't stop Solano going,'' said Robson. "He went away with Peru a couple of weeks ago and didn't play, but he's going again.

"After this he's got to decide what he's going to do about his international career.

"He had opted out, but now he's back in. This is one of the problems we have with him.

"The same thing applies to Acuna. The Peru-Chile match is the one which decides which country gets knocked out of the World Cup.

"I stand to lose one player and gain one player on one result. I'm trying to force the issue on Acuna not to travel.

"He came here on the strength that he had given up his international status. He did that of his own volition to get a contract here, but a new coach has persuaded him to think differently.''

l Andy O'Brien's hopes of a big-money move to Newcastle appear to be on the brink of collapse despite a gentlemen's agreement with Bradford.

Centre-back O'Brien was given a verbal promise by chairman Geoffrey Richmond two years ago that he would be notified of any approach by a Premiership club.

The unwritten get-out clause has alerted Newcastle boss Bobby Robson, who has been charting the progress of the promising Republic of Ireland international.

But it is understood the clubs differ in their valuation of O'Brien, with Newcastle believed to have offered £1m down, plus an extra £500,000 in clauses.

City are looking for at least £2m, although Jefferies is hoping to persuade O'Brien his future lies with Bradford.

''Andy has been kept informed by his agent that we don't want to let him go and that we are happy to keep him,'' said Jefferies